C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

cold start temperature sensor

Thread Tools
 
Search this Thread
 
Old Oct 1, 2024 | 01:54 PM
  #1  
BrianGreydan's Avatar
BrianGreydan
Thread Starter
7th Gear
All Eyes On Me
 
Joined: Oct 2024
Posts: 7
Likes: 1
Default cold start temperature sensor

Anyone know where I can source an ACDelco 212312 or GM 19244930 / 14084318 cold start sensor?
My 88 corvette has a hard cold start and the current sensor in the vehicle is causing poor idling and the car to bog down when driving.
Reply
Old Oct 1, 2024 | 02:11 PM
  #2  
Vets-Vet's Avatar
Vets-Vet
Drifting
Veteran: Navy
Photogenic
Photoriffic
Shutterbug
 
Joined: Jul 2022
Posts: 1,805
Likes: 365
From: Central Florida
Default

The cold start injector should be active for a maximum of 8 seconds. It should not be active with coolant above 95°f and is only active during key in crank position. I could see hard starting because it is not adding fuel but I don't see it affecting the car once started. If the cold start switch is shorted the injector/valve can be unpluged for proof, but I have never heard of the switch shorted. The info below is from an 87 but i can't see an 88 being different. Is the injector leaking ??
.

Last edited by Vets-Vet; Oct 1, 2024 at 03:03 PM.
Reply
Old Oct 1, 2024 | 03:46 PM
  #3  
BrianGreydan's Avatar
BrianGreydan
Thread Starter
7th Gear
All Eyes On Me
 
Joined: Oct 2024
Posts: 7
Likes: 1
Default

Thanks for the reply. However, I do need one of these switches as mine in faulting.
The bogging down occurs when I start driving after the hard cold start.
Reply
Old Oct 1, 2024 | 05:11 PM
  #4  
2011KLR's Avatar
2011KLR
Drifting
Veteran: Air Force
Photogenic
 
Joined: Sep 2022
Posts: 1,466
Likes: 382
From: Liberty, SC
2023 C4 of the Year Finalist - Unmodified
Default

Talk to Mikey....

FS (For Sale) 1986-88 Corvette Cold start injector - CorvetteForum - Chevrolet Corvette Forum Discussion
Reply
Old Oct 1, 2024 | 06:22 PM
  #5  
arbee's Avatar
arbee
Melting Slicks
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2003
Posts: 2,676
Likes: 810
From: Saskatoon Sask.
Default

Originally Posted by BrianGreydan
Thanks for the reply. However, I do need one of these switches as mine in faulting.
The bogging down occurs when I start driving after the hard cold start.
Why do people come to this forum looking for help if they are not going to READ and COMPREHEND the replies? Vets posted up a section of the FSM that clearly states " The circuit is activated only in the crank mode". Are you driving around with your starter engaged?
Reply
Old Oct 3, 2024 | 06:57 PM
  #6  
BrianGreydan's Avatar
BrianGreydan
Thread Starter
7th Gear
All Eyes On Me
 
Joined: Oct 2024
Posts: 7
Likes: 1
Default

Originally Posted by arbee
Why do people come to this forum looking for help if they are not going to READ and COMPREHEND the replies? Vets posted up a section of the FSM that clearly states " The circuit is activated only in the crank mode". Are you driving around with your starter engaged?
I read the "Chart A-9 Cold Start Valve Circuit Test"
It states as the coolant temperature goes up the "ON" time for the Cold Start Valve goes down.
The cold start and initial cold engine running is affected by this faulty sensor as stated by my GM mechanic. And I agree as the engine running does eventually smooth out as engine warms up.
Note: I have replaced all other functional components and sensors in the fuel system as well as the spark plugs, wires etc.

Last thing, when people seek help - don't be so rude mister know-it-all.
Reply
Old Oct 3, 2024 | 07:04 PM
  #7  
BrianGreydan's Avatar
BrianGreydan
Thread Starter
7th Gear
All Eyes On Me
 
Joined: Oct 2024
Posts: 7
Likes: 1
Default

Thanks for the help, but this doesn't look anything like the part on my '88.
Reply
Old Oct 3, 2024 | 07:14 PM
  #8  
tequilaboy's Avatar
tequilaboy
Melting Slicks
 
Joined: Aug 2003
Posts: 3,395
Likes: 393
From: Lakeville MI
Default

Easy enough to ground the switch if you want to test the impact of the cold start injector.
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

 Joe Kucinski
story-1

How Much Horsepower Every Corvette Engine "LOST" in 1972

 Joe Kucinski
story-2

Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

 Michael S. Palmer
story-3

Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

 Joe Kucinski
story-4

150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

 Joe Kucinski
story-5

8 Coolest Corvette Pace Cars (and Replicas) of All Time

 Verdad Gallardo
story-6

Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

 Joe Kucinski
story-7

Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

 Verdad Gallardo
story-8

Top 10 Corvettes Coming to Mecum Indy 2026!

 Brett Foote
story-9

Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

 Michael S. Palmer
Old Oct 4, 2024 | 12:15 AM
  #9  
arbee's Avatar
arbee
Melting Slicks
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2003
Posts: 2,676
Likes: 810
From: Saskatoon Sask.
Default

Originally Posted by BrianGreydan
I read the "Chart A-9 Cold Start Valve Circuit Test"
It states as the coolant temperature goes up the "ON" time for the Cold Start Valve goes down.
The cold start and initial cold engine running is affected by this faulty sensor as stated by my GM mechanic. And I agree as the engine running does eventually smooth out as engine warms up.
Note: I have replaced all other functional components and sensors in the fuel system as well as the spark plugs, wires etc.

Last thing, when people seek help - don't be so rude mister know-it-all.
So did you also pick up on the fact it says it is ONLY ACTIVE WHILE CRANKING? That it GETS ITS POWER FROM THE STARTER SOLINOID? You don't have to be a "know-it-all" to READ the English language. It's not that difficult unless one didn't make it past grade six.
Reply
Old Oct 4, 2024 | 09:10 AM
  #10  
2011KLR's Avatar
2011KLR
Drifting
Veteran: Air Force
Photogenic
 
Joined: Sep 2022
Posts: 1,466
Likes: 382
From: Liberty, SC
2023 C4 of the Year Finalist - Unmodified
Default

(sigh) Welcome to the forum Brian.
Reply
Old Oct 4, 2024 | 02:15 PM
  #11  
BrianGreydan's Avatar
BrianGreydan
Thread Starter
7th Gear
All Eyes On Me
 
Joined: Oct 2024
Posts: 7
Likes: 1
Default

Again, stop being ******* rude.
I still need a new cold start switch not the cold start injector.
So if you can't help just **** OFF
Why even put your two cents worth into the thread.

New member to this forum and my first post gets an ******* like you responding.
Reply
Old Oct 4, 2024 | 02:45 PM
  #12  
Vets-Vet's Avatar
Vets-Vet
Drifting
Veteran: Navy
Photogenic
Photoriffic
Shutterbug
 
Joined: Jul 2022
Posts: 1,805
Likes: 365
From: Central Florida
Default

We are trying to explain to you that the cold start only has power when the starter is engaged. It only has ground with the cold start switch closed. If you want a cold start switch call around to a corvette junk yard and get one. Part of what is done in here is to educate. The reason for the hard ball is the switch is not readily available so we were offering you some suggestions before spending money to help you. People in here are very intelligent, Arbee being one of them. So intelligent are these folks that I believe we see mechanics all the time come through here that can't fix a customers C4. People get cross at times, people are stern at times, it is common, but your language is not.

The part is no longer made and is rare. Some numbers will cross on some websites but they are actually an EGR switch with an 85 second delay.
My suggestion, 1. go to a junk yard 2. Be nice to these people, they are the best in the world at C4 corvettes. 3. Show your mechanic these posts, unless this is a rare case, he is wrong. 4. If the switch is turning the valve on somehow, unplug the valve/injector, another thing we tried to tell you. 5. If the valve is still putting fuel in the system after it is unplugged, it would be the valve and not the switch. 6. Find out if this has all been confused with the coolant temperature sensor right next to it. If I remember right the threads on the both the cold start and coolant temp are the same, they are swapped in a lot of vehicles. We are trying to educate you but you keep saying the same thing. If that is the case, go to a junk yard and get one.

Last but not least you list an impossibillity, cold start not working so it is a hard start. No fuel from cold start??
causing poor idling and the car to bog down when driving. Now when it should be off it is giving fuel ???
Which one is it ???

.
.

Last edited by Vets-Vet; Oct 4, 2024 at 03:39 PM.
Reply
Old Oct 4, 2024 | 03:01 PM
  #13  
BrianGreydan's Avatar
BrianGreydan
Thread Starter
7th Gear
All Eyes On Me
 
Joined: Oct 2024
Posts: 7
Likes: 1
Default

Arbee maybe intelligent (doubtful) but he is rude as hell and resorts to insulting new forum members.
His method of education is not appreciated.
You on the other hand are helpful and polite with you posts.
I however will use any language I want when dealing with someone like Arbee.
I had such high hopes for this forum....

My GM mechanic is very good with over 40 years experience and I trust him.
Reply
Old Oct 4, 2024 | 08:58 PM
  #14  
arbee's Avatar
arbee
Melting Slicks
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2003
Posts: 2,676
Likes: 810
From: Saskatoon Sask.
Default

Originally Posted by BrianGreydan
Arbee maybe intelligent (doubtful) but he is rude as hell and resorts to insulting new forum members.
His method of education is not appreciated.
You on the other hand are helpful and polite with you posts.
I however will use any language I want when dealing with someone like Arbee.
I had such high hopes for this forum....

My GM mechanic is very good with over 40 years experience and I trust him.
Sorry to knot your panties dude. I was going to suggest that you might be a bit old to be getting butthurt like a gen Y or Z, but then I seen California and it all makes sense. Vets even tried to explain it to you "nicely" and you STILL won't listen. Not wasting any more time.
Reply
Old Oct 4, 2024 | 11:30 PM
  #15  
IHBD's Avatar
IHBD
Melting Slicks
All Eyes On Me
Shutterbug
Top Answer: 5
Pro Mechanic
 
Joined: Nov 2016
Posts: 2,253
Likes: 3,074
From: So Cal
2023 C4 of the Year Finalist - Unmodified
Default

[QUOTE=BrianGreydan;1608224704]
It states as the coolant temperature goes up the "ON" time for the Cold Start Valve goes down.
Yes. But only when the key is in CRANK position. There is a heating element in the Thermo Time Switch. When there is power to the TTS, the heating element is powered, heating the bimetalic element that holds the switch contacts closed. Either coolant temperature, or the heater element, can cause the contacts to open. The higher the temperature in the switch, the less time the contacts will be allowed to be closed before opening, disabling the injector. Usually, the engine starts and the key is released long before the heating element opens the contacts.

The cold start and initial cold engine running is affected by this faulty sensor as stated by my GM mechanic.
Let's leave out the "cold rough running" for now.

In the context of Cold Start, the definition of "Cold" is when the coolant temperature and the ambient temperatures are the same. Such as after the engine sits overnight. "Cold" has nothing to do with the weather.

The Cold Start Injector is activated at coolant temperatures below 95F (or 105, depends on which year FSM you read.). Once the key is released, the CSI is not powered and has no influence on the way the engine runs.


And I agree as the engine running does eventually smooth out as engine warms up.
Ok, you "agree", but both yours and your mechanic's diagnosis is faulty. The rough running during warm-up can not be caused by the TTS, because the TTS / CSI are inactive once the key is released from CRANK. Again, there is no power to either of them once the engine is running.

You have two issues. The hard start. And the rough running during warm up. The 85-88 requires a functioning Cold Start Injector system for easy starts after an overnight sit. It should fire in less than a second of cranking after an overnight sit. If it doesn't, the CSI is probably not working. Fix the hard start first, then move on to the rough running in warm-up.

Three really simple tests:
A: Is there power on the purple wire at the injector and the TTS with the key in CRANK? If = NO, there is a fuse behind the Driver Information Center. Check that first.
B: With a "cold" engine, ie it sat overnight, is there power across both wires of the Cold Start Injector connector with the key in CRANK? If = NO, the TTS is faulty, OR the engine is too warm. If = YES, go to C.
C: Connect your fuel pressure test gauge to the fuel rail. Cycle the key to run the fuel pump. Turn off key and note the fuel pressure. Apply 12V to the two terminals on the CSI. Does the pressure drop? If = NO, the injector is faulty.



Last edited by IHBD; Oct 4, 2024 at 11:37 PM.
Reply

Get notified of new replies

To cold start temperature sensor





All times are GMT -4. The time now is 10:55 PM.

story-0
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

Slideshow: 10 reasons why the C6 Z06 is still a performance benchmark after 20 years.

By Joe Kucinski | 2026-05-27 17:20:09


VIEW MORE
story-1
How Much Horsepower Every Corvette Engine "LOST" in 1972

Slideshow: How much horsepower every Corvette engine lost in 1972.

By Joe Kucinski | 2026-05-27 16:54:53


VIEW MORE
story-2
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-3
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-4
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-5
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE
story-6
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

Slideshow: Ranking the top 10 Corvette engines by torque output.

By Joe Kucinski | 2026-05-05 11:58:09


VIEW MORE
story-7
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

Slideshow: A Corvette pace car nearly matching IndyCar speeds sounds exaggerated, until you look at the numbers.

By Verdad Gallardo | 2026-05-04 20:03:36


VIEW MORE
story-8
Top 10 Corvettes Coming to Mecum Indy 2026!

Among a rather large group of them.

By Brett Foote | 2026-05-04 13:56:44


VIEW MORE
story-9
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE